1 Cells + Organelles Flashcards
1
Q
Define a cell
A
Basic unit for which living organisms are made, consisting of an aqueous solution or organic molecules enclosed by a membrane
2
Q
Describe an important factor of eukaryotic cells
A
Eukaryotic cells and organised and compartmentalised. Organelles are sub cellular structures which carry out specific functions within the cell.
3
Q
List components of a typical animal cells
A
- Nucleus
- Endoplasmic reticulum
- Golgi Apparatus
- Mitochondria
- Plasma Membrane
- Peroxisomes
- Lysosomes
- cytoskeleton - Microfilaments, Microtubules, Intermediate filaments
4
Q
Describe structure of organelles
A
- sub- cellular compartment ( eukaryotic cells)
- usually membrane bound - ribosomes
- specialised for a unique function
5
Q
Which organelle in a eukaryotic cell is not membrane bound
A
Ribosome
6
Q
Describe structure and function of a nucleus
A
- membrane bound which contains DNA
7
Q
What structure covers the nucleus
A
- nuclear membrane (envelope)
8
Q
Which structure in the nuclear membrane allows for substances to pass between the cytoplasm and nucleus
A
Pores in the nuclear membrane
9
Q
Name the structure found underneath the nucleus and it’s function
A
Nuclear lamina is found underneath the nucleus and accumulates molecules
10
Q
What two structures form chromatin
A
DNA and histones
11
Q
List the 4 structures which are associated with the nucleus
A
- Nuclear membrane
- Nuclear lamina
- chromatin
- Nucleolus
12
Q
Describe the function of Nucleolus of the nucleus
A
- site of ribosomal RNA and ribosome synthesis
13
Q
List the components which compose the plasma membrane
A
- phospholipid bilayer
- cholesterol
- carbohydrates
- proteins
- lipid/ membrane rafts
14
Q
Describe the main function of the plasma membrane
A
Regulates and controls substances which leave and enter the cell as well as detecting stimuli anc responding accordingly.
Plasma membrane forms an interface with the external environment and the cell
15
Q
What is the function of cholesterol in the plasma membrane
A
Cholesterol improves fluidity of the plasma membrane and is concentrated in the lipid rafts
16
Q
What is the function of carbohydrates and proteins in the plasma membrane
A
- perform specific functions within the cell
17
Q
Describe the structure and function of lipid/ membrane rafts in the plasma membrane
A
Lipid rafts are organised into specific domains. These are concentrating signalling receptors.
Increased concentration of cholesterol in plasma membrane ( cholesterol increases fluidity)
18
Q
Describe the structure and function of Glycocalyx in plasma membrane
A
- layer of carbohydrate which covers the cells
- functions as cell recognition
- stomach is lined with glycocalyx where digestive enzymes are stored
19
Q
What are the two phospholipid types found in the plasma membrane
A
- phosphatidycholine
- phosphatidylserine
20
Q
In which layer is the phosphatidylcholine found
A
Outer layer of the plasma membrane
21
Q
In which layer is phosphatidylserine found in the plasma membrane
A
- inner layer of the plasma membrane
22
Q
What is the main function of the Mitochondria
A
- produces energy if the form of ATP
- apoptosis -DNA stress/ damage
23
Q
Describe the structure of the mitochondria
A
- outer membrane
- intermembrane space
- inner membrane (Cristae)
- Matrix
24
Q
What is outer membrane of the mitochondria composed of
A
Outer membrane is composed of pyruvate - selectively permeable
25
What process takes place in the inner membrane (cristae) of mitochondria
- electron transport chain
26
What does the matrix of mitochondria contain
- enzymes for citric acid cycle and TCA cycle
27
Through which processes does the mitochondria produce ATP
- tricarboxylic acid TCA / Kerbs Cycle
- electron transport chain - cytochrome c on inner membrane
- Oxidative phosphorylation
28
How does the mitochondria carry out apoptosis
- release of cytochrome C in mitochondria to cytosol which initiates apoptosis
29
Name the 2 types of Endoplasmic Reticulum
- Rough Endoplasmic reticulum
- Smooth Endoplasmic reticulum
30
List features of the Rough Endoplasmic reticulum
- associated with ribosomes
- protein synthesis
- protein folding
- protein modification
31
List the features of the smooth Endoplasmic reticulum
- no ribosomes
- lipid synthesis
- calcium storage
32
Describe the structure of the Golgi apparatus
- stack of flattened membrane bound stacks - cisternae and vesicles
33
Describe the function of the Golgi apparatus
- proteins received from the ER
- proteins are modified and sorted into eventual destinations either for use within or out with the cell.
34
Describe the function of lysosomes
- Degrade unwanted molecules
- Contain 50 degradative enzymes
- optimal ph 5
35
Describe the function of peroxisomes
- perform large number of biochemical reactions - membrane bound
- diverse family of peroxisomes ( different subset of reactions)
- contain oxidative enzymes - catalyse
- breakdown of fatty acids - B- oxidation
36
Define amphipathic
Molecules which is both polar and non- polar
37
Give an example of a cell structure which is amphipathic
- plasma membrane
38
Define a phospholipid
- lipid composed of phosphate polar heads and two fatty acid side chains - one saturated and the other unsaturated
39
Define lamellipodia
- Lamellipodia is a micro- filament based membrane protrusions which allows the cell to move
40
Define filopodia
- very small spikes in the micro filament based protrusions of the plasma membrane involved in cell motility
41
There are 4 main blood groups A, B, AB & O which are determined by the presence of specific molecules of the plasma membrane on red blood cells (erythrocytes).
What type of molecule determines the ABO blood grouping?
Carbohydrates
42
Describe the functions of cytoskeleton of a cell
- organise cell structure
- maintains correct shape of cell
- supports fragile plasma membrane
- provides mechanical linkages that let cell or tissue to bear stres
- facilitates movement of organelles
- allows cell to adopt specific behaviours - growth, division & motility
43
List the 3 types of cytoskeleton
Microfilament
Microtubules
Intermediate filaments
44
Describe the difference between Microtubules, microfilaments and intermediate filaments
- Microtubules and microfilaments are dynamic structures as they change in response to different situations
- intermediate filaments are static and stable
45
What role do intermediate filaments play
Structural
46
What is the function of intermediate filaments
Provide mechanical strength
47
Which type of intermediate filaments are present in skin
Keratin family
48
Keratin family are a form of intermediate filaments found in which type of cells
Skin epithelial cells
49
Which type of intermediate filaments are present in fibroblasts
Vimentin
50
Vimentin is a type of intermediate filament which is found …
Fibroblasts
51
What’s type of intermediate filaments are found in nuclei of eukaryotic cells
Lamins
52
Lamins are a type of intermediate filament and where are these found
In nucleus of eukaryotic cells
53
In which layer of the skin is the intermediate filament keratin present
Epidermis = keratin ( intermediate filament)
54
In which layer of the skin is the intermediate filament vimentin present
Dermis in fibroblasts ( vimentin - intermediate filament)
55
Nuclear lamina is an intermediate filament, describe its function?
- composed of lamins
- nuclear organisation
- nuclear membrane support
- chromatin organisation
56
List the functions of Microtubules
- cell movement
- mitotically spindle fibres - separation of cells in mitosis
- intracellular transport of organelles
57
What are Microtubules composed of
- polymers of alpha and beta tubulin
58
Which two molecules help with intracellular organelle transport in microtubules
- Kinesins = move cargo away from centrosomes
- Dunedin’s = move cargo towards the centrosome
59
What is an axoneme
Component of cytoskeleton
60
Name two axonemes
Flagella and cilia
61
Describe the function flagella and cilia have on cell
- allow for movement and bending
62
What are cilia and flagella composed of
- microtubules and Dynein
63
Name two types of membrane extensions in a cell
Lamellipodia and filopodia
64
What are microfilaments
Polymers of actin and needed for wound healing
65
What are the functions of microfilaments on cells
- cytoplasm allows for a change in cell shape
- microvilli are cell projections
66
What are the functions of lamellipodia and filopodia
- help cell motility (cell movement)
67
What is the main function of intermediate filaments
Provide mechanical strength
68
What is the main function of microtubules
Help with intracellular transport - dynein (towards centrosome) & Kinesins (away centrosomes)
Mitosis and movement
69
What is the function of microfilaments
Change cells shape, cell motility, and provide cell structure
70
What are cell junctions
Transmembrane protein complexes
71
State function of cell junctions
Connect plasma membrane to adjacent cells, basement membrane and cytoskeleton
72
What is the function of cell- cell junctions
These anchor cells to one another
73
Name two types of cell- cell junctions
Adherens
Desmosomes
74
Which type of junctions help cells to be anchored to the ECM
Cell- ECM junctions
75
Name two types of cell ECM junctions
- focal adhesions
- Hemidesmosomes
76
Focal and adhesion junctions form which type of anchoring junctions
ECM junctions which anchor the cells through the Extracellular junction
77
Name two types of cytoskeleton junctions
Actin
Intermediate filaments
78
Actin & intermediate filaments are part of which type of cell junctions
Cytoskeleton junctions
79
Which two type of cell junctions connect to intermediate filaments
Hemidesmosomes - cell ECM junctions
Desmosomes - Cell - Cell junctions
80
Name two types of cell junctions which connect to actin
Focal adhesions - ECM junctions
Adherents - Cell - Cell junctions
81
What is the function of adherents and focal adhesions junctions - connect to actin
Regulate and adhere to change in the cytoskeleton - increasing flexibility
82
What do hemidesmosomes and desmosomes attach to
Intermediate filament
83
What is the function of hemidesmosomes ( ECM junctions) and desmosomes ( Cell- cell junctions)
These are strong junctions which form strong and stable tissue
84
What is the function of tight junctions
- Act as gates or fences
- polarises the cell as it consists of separate domains ( apical = top) and (basolateral = bottom)
85
What is the function of a gate tight junction
Regulates paracellular permeability - controllers substances moving between cells
86
What is the function of fence tight junction
Forms an apical or basolateral intramembrane diffusion barrier
- prevents the apical (top) substances from mixing with the lower section basolateral (bottom)
87
What is the function of a tight junction
- separates the cells top (apical) section from the bottom ( basolateral)
88
Which type of cells contain a distinct domains
- skin cells in epidermis
- epithelial cells
89
What is the purpose of cells having an apical and basolateral domain
- cell is polarised
- lower and upper domains of the cell have different functions and direction
90
What is another name for channel forming junctions
GAP junctions
91
What is a GAP junction
Channel forming junction - forms small channels between adjacent cells
92
What is an advantage of gap junctions
Gap junctions allows for chemical and electrical communication between cells
93
What is a gap junction composed of
Hexamers of Connexins
94
One of the hallmarks of cancer cells is that cells move away from one site, the primary tumour. This is done by detaching from the neighbouring cells and migrate away from primary tumour.
What molecule is decreased in tumours?
E- Cadherin- component in cell junctions ( adherin junctions). These junctions are lost during cancer progression
